Goddess and pitman by museum (7)
I believe the answer is:
minerva
'goddess' is the definition.
(thesaurus)
'pitman by museum' is the wordplay.
'pitman' becomes 'miner' (I've seen this before).
'by' is a charade indicator (letters next to each other).
'museum' becomes 'va' (Victoria and Albert Museum, or 'V and A').
'miner'+'va'='MINERVA'
'and' acts as a link.
(Other definitions for minerva that I've seen before include "Roman counterpart of Athene" , "deity of wisdom" , "female of great wisdom" , "Roman goddess of learning" , "Roman goddess of crafts and wisdom - a vermin (anag)" .)