Cheer up when the right man is about (8)
I believe the answer is:
brighten
'cheer up' is the definition.
(I've seen this before)
'the right man is about' is the wordplay.
'man' becomes 'ben' ().
'is about' means one lot of letters goes inside another.
'right' placed inside 'ben' is 'BRIGHTEN'.
'when' acts as a link.
(Other definitions for brighten that I've seen before include "Illuminate, cheer up" , "Cheer up; clear up" , "Berthing (anag.)" , "Polish" , "Provide illuminations" .)