Trust son and go out and count sheep (4,3,4)
I believe the answer is:
toss and turn
'count sheep' is the definition.
(thesaurus)
'trust son and go out' is the wordplay.
'go out' indicates an anagram.
'trust'+'son'+'and'='trustsonand'
'trustsonand' anagrammed gives 'TOSS AND TURN'.
'and' acts as a link.
(Other definitions for toss and turn that I've seen before include "Be restless (in bed)" , "Be unable to sleep" , "count sheep" , "rest uneasily" , "Be wakeful and fidgety" .)