In the cellar of the Georgetowne Seafood House is a small room called the Pirates' Hideaway in which is heard, Thursdays through Saturdays, some of the most professional and exciting small combo jazz this city presently offers. Pianist Dick Morgan presides, and last night he was in the company of regulars Dave Mindenhall and Jimmy West at the drums. (Bassist Paul Langosch was filling in for Dave Wundro.)

Morgan has, in addition to two strong hands and estimable skills with which to guide them, a superior dramatic sense and a gift for structure. He is given to building up numbers by degrees, from lightly tinkling beginnings to roaring finishes, as he did with the opening "Autumn Leaves" and the closing, unnamed group original.

The others gave Morgan such subtle support that at times they were almost felt rather than heard, but when the occasion called for it each was out front contributing strong individual statements. Mindenhall's single note lines were as fleet as the wind and West's stick work had a cracked-whip sharpness. Langosch was a steady anchor beneath all and a supple soloist.

"My Favorite Things," was a good display of Morgan's feeling for space and economy of expression in the first half and then, after a moment of dead air, he swaggered and stomped to a block-chorded Errol Garner conclusion.