Fix pipe supplying water perhaps in field (6)
I believe the answer is:
domain
'field' is the definition.
(I know that field can be written as domain)
'fix pipe' is the wordplay.
'fix' becomes 'do' (I've seen this in other clues).
'pipe' becomes 'main' (main is a kind of pipe).
'do'+'main'='DOMAIN'
'supplying water perhaps in' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for domain that I've seen before include "District or area - or range of influence" , "Special region, area of expertise" , "Sphere of activity" , "Sphere or territory" , "Territory over which someone reigns" .)