High-flyer in Navy plugging point repeatedly (4)
I believe the answer is:
erne
'high-flyer' is the definition.
'navy plugging point repeatedly' is the wordplay.
'point repeatedly' means two replacements for 'point'.
'navy' becomes 'rn' (abbreviation for Royal Navy).
'plugging' means one lot of letters goes inside another (I've seen this in other clues).
'point' becomes 'e' (E is an example).
'point' becomes 'e' (E is an example**).
'e'+'e'='ee'
'rn' going inside 'ee' is 'ERNE'.
'in' acts as a link.
(Other definitions for erne that I've seen before include "Island-studded lake in Fermanagh" , "Lough of the North" , "White-tailed eagle" , "flyer in the main" , "'Sea-eagle, river and lough (4)'" .)