Official weather forecast possibly a burden (7)
I believe the answer is:
refrain
'a burden' is the definition.
(I've seen this before)
'official weather forecast' is the wordplay.
'official' becomes 'ref' (match official in football, say).
'weather forecast' becomes 'rain' (I've seen this in another clue).
'ref'+'rain'='REFRAIN'
'possibly' acts as a link.
(Other definitions for refrain that I've seen before include "Forbear from chorus?" , "Chorus of a song" , "Chorus; keep away (from)" , "burden" , "Much repeated saying" .)