English teacher cautious in absence of head delegate (8)
I believe the answer is:
emissary
'delegate' is the definition.
(thesaurus)
'english teacher cautious in absence of head' is the wordplay.
'english' becomes 'e' (abbreviation).
'teacher' becomes 'miss' (I've seen this before**).
'cautious' becomes 'wary' ('wary' can be similar in meaning to 'cautious').
'in absence of head' means to remove the first letter.
'wary' with its initial letter taken off is 'ary'.
'e'+'miss'+'ary'='EMISSARY'
(Other definitions for emissary that I've seen before include "one dispatched officially" , "Spy" , "I'm sent!" , "Government agent" , "Diplomatic representative" .)