Stands? Hard in wellies, perhaps! (6)
I believe the answer is:
booths
'stands?' is the definition.
'hard in wellies perhaps' is the wordplay.
'hard' becomes 'h' (abbreviation used in pencil classifications).
'in' is an insertion indicator.
'wellies perhaps' becomes 'boots' (Wellington boots).
'h' inserted inside 'boots' is 'BOOTHS'.
(Other definitions for booths that I've seen before include "Small shops, at a fair say" , "Small temporary stalls, for voting, say" , "Small temporary shops, at a market say" , "Small area, for voting say" , "Small areas, for voting say" .)