Reached top of cold water with arms at side (7)
I believe the answer is:
climbed
'reached top of' is the definition.
'cold water with arms at side' is the wordplay.
'cold water' becomes 'c' (symbol for the cold tap).
'with arms' becomes 'limbed'.
'at side' is a charade indicator (letters next to each other).
'c'+'limbed'='CLIMBED'
(Other definitions for climbed that I've seen before include "Ascended" , "rose" .)