Heather wanting a boy (4)
I believe the answer is:
eric
'boy' is the definition.
(I've seen this before)
'heather wanting a' is the wordplay.
'heather' becomes 'erica' (I've seen this before).
'wanting' is a deletion indicator (to want something can mean to lack it or need it).
'erica' with 'a' taken away is 'ERIC'.
(Other definitions for eric that I've seen before include "Boy's name" , "-- Sykes; -- Idle" , "-- Idle; -- Morecambe" , "-- Idle, comedian" , "--, or Little by Little (Dean Farrar)" .)