Initially heading as if for an Israeli port (5)
I believe the answer is:
haifa
'israeli port' is the definition.
(I've seen this in another clue)
'initially heading as if for an' is the wordplay.
'initially' indicates taking the first letters.
'for' means one lot of letters go next to another.
'an' becomes 'a'.
The initial letters of 'heading as' is 'ha'.
'ha'+'if'+'a'='HAIFA'
(Other definitions for haifa that I've seen before include "Mediterranean port" , "Middle East city" , "Port of N. Israel" , "Chief port of Israel" , "Israel's main port" .)