Not all solicitors are lawful! (5)
I believe the answer is:
licit
'lawful' is the definition.
(synonyms)
'not all solicitors are' is the wordplay.
'not all' indicates a hidden word.
'LICIT' can be found hidden inside 'solicitors are'.
(Other definitions for licit that I've seen before include "Acceptable" , "Allowable" , "in order" , "Legal" , "Permitted by law" .)