Forbear to call the ref a shower (7)
I believe the answer is:
refrain
'forbear' is the definition.
(I know that forbear can be written as refrain)
'ref a shower' is the wordplay.
'a shower' becomes 'rain' (rainfall).
'ref'+'rain'='REFRAIN'
'to call the' acts as a link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for refrain that I've seen before include "Forbear from chorus?" , "Lines repeated at the end of each verse" , "Much repeated saying" , "Main part of song - do not do it" , "The repeated lines at the end of verses" .)