Nancy's old serving man turned up to frame painting (5)
I believe the answer is:
poilu
'nancy's old serving man' is the definition.
I can't judge whether this defines the answer.
'turned up to frame painting' is the wordplay.
'turned' is a reversal indicator.
'to frame' is an insertion indicator.
'painting' becomes 'oil' (oil painting is a kind of painting).
'up' reversed gives 'pu'.
'pu' going around 'oil' is 'POILU'.
Can you help me to learn more?
(Other definitions for poilu that I've seen before include "Old soldier" , "simple soldat" , "French private soldier" , "Fighter at Verdun" .)