Composer with support at front of harpsichord to take manuscript (6)
I believe the answer is:
brahms
'composer' is the definition.
(Brahms is an example)
'support at front of harpsichord to take manuscript' is the wordplay.
'support' becomes 'bra' (a support for the breasts**).
'at' says to put letters next to each other.
'front of' suggests taking the first letters.
'to take' means one lot of letters go next to another.
'manuscript' becomes 'ms' (abbreviation for manuscript).
The initial letter of 'harpsichord' is 'h'.
'bra'+'h'+'ms'='BRAHMS'
'with' is the link.
(Other definitions for brahms that I've seen before include "19th century German composer, known for Lullaby" , "Composer of a well-known lullaby published in 1868" , "German Romantic composer" , "'Bah, Mrs, he's a composer (6)'" , "Composer of A German Requiem" .)