Likeness to rap artist regularly is awkward (8)
I believe the answer is:
Here is my best explanation:
'likeness' is the definition.
(portrait is a kind of likeness)
'to rap artist regularly is awkward' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'is awkward' indicates an anagram.
The alternating letters of 'artist' are 'rit'.
'toraprit' is an anagram of 'PORTRAIT'.