Feline receives welcome warning (6)
I believe the answer is:
caveat
'warning' is the definition.
(caveat is a kind of warning)
'feline receives welcome' is the wordplay.
'feline' becomes 'cat' (I've seen this before).
'receives' indicates putting letters inside.
'welcome' becomes 'ave' (I've seen this before).
'cat' enclosing 'ave' is 'CAVEAT'.
(Other definitions for caveat that I've seen before include "'Caution, warning (6)'" , "Reservation" , "Warning (of conditions)" , "Caution - qualification" , "Legal caution" .)