Summer party Ms Summers set up (5)
I believe the answer is:
donna
'summer' is the definition.
(musician Donna Summer)
'party ms summers set up' is the wordplay.
'party' becomes 'do' (do is a kind of party).
'ms summers' becomes 'ann' (Ann Summers is a lingerie company).
'set up' is a reversal indicator.
'ann' reversed gives 'nna'.
'do'+'nna'='DONNA'
(Other definitions for donna that I've seen before include "Title of Spanish or Portuguese lady" , "Title of Spanish or Italian lady" , "Italian woman of rank" , "See 10" , "Female" .)