Foot of water in cathedral office (7)
I believe the answer is:
spondee
'foot' is the definition.
(type of metrical foot in poetry)
'water in cathedral office' is the wordplay.
I cannot quite understand how this works, but
'water' could be 'pond' (pond is a kind of water) and 'pond' is found within the answer.
The remaining letters 'see' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'of' acts as a link.
Can you help me to learn more?
(Other definitions for spondee that I've seen before include "Metric foot of two long syllables" , "No speed required for poetic metrical foot" , "bit of verse" .)