Observe drinks holding temperature with sun (7)
I believe the answer is:
witness
'observe' is the definition.
(I've seen this before)
'drinks holding temperature with sun' is the wordplay.
'drinks' becomes 'wines' (wine is a kind of drink).
'holding' is an insertion indicator.
'temperature' becomes 't' (abbreviation).
'with' says to put letters next to each other.
'sun' becomes 'S' (abbreviation).
'wines' enclosing 't' is 'witnes'.
'witnes'+'s'='WITNESS'
(Other definitions for witness that I've seen before include "It's news (anag.)" , "One who saw an event, may give evidence" , "Court testifier" , "Onlooker" , "One giving evidence" .)