Popular pair in field getting decoration (9)
I believe the answer is:
paintwork
'decoration' is the definition.
(I've seen this before)
'popular pair in field' is the wordplay.
'popular' becomes 'in'.
'pair' becomes 'two' (I've seen this before**).
'in' means one lot of letters goes inside another.
'field' becomes 'park'.
'in'+'two'='intwo'
'intwo' inserted inside 'park' is 'PAINTWORK'.
'getting' is the link.
(Other definitions for paintwork that I've seen before include "Coats maybe" , "matt and gloss?" , "Decoration" .)