Artist has to combat endless depression (6)
I believe the answer is:
warhol
'artist' is the definition.
(Andy Warhol)
'to combat endless depression' is the wordplay.
'to combat' becomes 'war' (I've seen this before).
'endless' means to remove the last letter.
'depression' becomes 'hole' (depression can mean a hole or crater).
'hole' with its last letter taken off is 'hol'.
'war'+'hol'='WARHOL'
'has' is the link.
(Other definitions for warhol that I've seen before include "Andy ......., pop art icon of the 1960s" , "Leader of the Pop Art movement" , "Modern artist" , "15-minute artist?" , "US exponent of pop art, d. 1987" .)