Island road heading north through rocky outcrop (5)
I believe the answer is:
timor
'island' is the definition.
(I've seen this before)
'road heading north through rocky outcrop' is the wordplay.
'road' becomes 'MI'.
'heading north' says the letters should be written in reverse.
'through' means one lot of letters goes inside another (inserted letters go through the word).
'rocky outcrop' becomes 'tor' (term for a hill).
'mi' in reverse letter order is 'im'.
'im' placed within 'tor' is 'TIMOR'.
(Other definitions for timor that I've seen before include "East . . . . ., became independent of Indonesia in 2002" , "Island north of Australia" , "East Indies island NW from Darwin" , "Indonesian island" , "SE Asian island" .)