Look for water: measure round wicket (5)
I believe the answer is:
dowse
'look for water' is the definition.
(I've seen this before)
'measure round wicket' is the wordplay.
'measure' becomes 'dose' (dose is a kind of measure).
'round' means one lot of letters goes inside another.
'wicket' becomes 'w'.
'dose' enclosing 'w' is 'DOWSE'.
(Other definitions for dowse that I've seen before include "Search for water using hazel twig" , "Search for water using hazel rod" , "Search for underground water using rod" , "twitch" , "Prospect for water" .)