Red suns set in strip (7)
I believe the answer is:
undress
'strip' is the definition.
(I know that strip can be written as undress)
'red suns set' is the wordplay.
'set' is an anagram indicator (instruction to set the letters).
'red'+'suns'='redsuns'
'redsuns' is an anagram of 'UNDRESS'.
'in' acts as a link.
(Other definitions for undress that I've seen before include "Sunders (anag)" , "Take one's clothes off" , "Remove clothes, strip" , "Strip, take off clothes" , "Nudity" .)