Check delivered sink and shower unit (8)
I believe the answer is:
raindrop
'shower unit' is the definition.
(I've seen this in another clue)
'check delivered sink' is the wordplay.
'check' becomes 'rein' (both can mean to control or limit).
'delivered' indicates a 'sounds like' (homophone) clue (delivered verbally).
'sink' becomes 'drop' (synonyms).
'rein' sounds like 'rain'.
'rain'+'drop'='RAINDROP'
'and' acts as a link.
(Other definitions for raindrop that I've seen before include "Part of a shower" , "Bead of water from a cloud" , "Unit of moisture precipitated from sky" , "Water from the heavens" , "One of many in a shower" .)