Get high at first with father in capital (7)
I believe the answer is:
baghdad
'capital' is the definition.
(capital of Iraq)
'get high at first with father' is the wordplay.
'get' becomes 'bag' (bag can mean to secure or obtain).
'at first' says to take the initial letters.
'with' is a charade indicator (letters next to each other).
'father' becomes 'dad' (informal term for father).
The initial letter of 'high' is 'h'.
'bag'+'h'+'dad'='BAGHDAD'
'in' is the link.
(Other definitions for baghdad that I've seen before include "Iraqi capital" , "capital abroad" , "Capital of Iraq" , "city abroad" .)