A son restricted by talent for daydreaming (6)
I believe the answer is:
absent
'daydreaming' is the definition.
(thesaurus)
'a son restricted by talent' is the wordplay.
'son' becomes 's'.
'restricted by' means one lot of letters goes inside another (I've seen this in other clues).
'talent' becomes 'bent' (bent is a kind of talent).
's' inserted inside 'bent' is 'bsent'.
'a'+'bsent'='ABSENT'
'for' acts as a link.
(Other definitions for absent that I've seen before include "lack of attention" , "nowhere to be seen" , "Away" , "AWOL" , "Missing or dreamy" .)