Letter by female artist at end of guide camp (10)
I believe the answer is:
effeminate
'camp' is the definition.
(I've seen this before)
'letter by female artist at end of guide' is the wordplay.
'letter' becomes 'eff' (name for the letter F).
'by' is a charade indicator (letters next to each other).
'female artist' becomes 'emin' (British artist Tracey Emin).
'end of' suggests the final letters.
The final letter of 'guide' is 'e'.
'eff'+'emin'+'at'+'e'='EFFEMINATE'
(Other definitions for effeminate that I've seen before include "sissy?" , "camp" , "(Of a man) having female characteristics" , "Womanly" , "Acting like a woman" .)