Leader of strategists in Carthage prepared to invade (4-5)
I believe the answer is:
gate-crash
'invade' is the definition.
(eg invade a party)
'leader of strategists in carthage prepared' is the wordplay.
'leader of' suggests taking the first letters.
'in' means one lot of letters goes inside another.
'prepared' is an anagram indicator.
The initial letter of 'strategists' is 's'.
'carthage' with letters rearranged gives 'gatecrah'.
's' put inside 'gatecrah' is 'GATE-CRASH'.
'to' acts as a link.
(Other definitions for gate-crash that I've seen before include "Attend private party without invitation" , "Enter (a party) without an invitation" , "Intrude on private party without invitation" , "Enter uninvited" , "Arrive uninvited" .)