Tory leader's little affected (4)
I believe the answer is:
twee
'affected' is the definition.
(I've seen this before)
'tory leader's little' is the wordplay.
'tory leader' becomes 't' (I've seen this in other clues).
'little' becomes 'wee' ('wee' can be similar in meaning to 'little').
't'+'wee'='TWEE'
(Other definitions for twee that I've seen before include "Affected quaint" , "Affectedly pretty" , "Niminy-piminy" , "Excessively cute" , "rather quaint" .)