Notice pool, internally, is a foot (7)
I believe the answer is:
spondee
'a foot' is the definition.
(type of metrical foot in poetry)
'notice pool internally' is the wordplay.
'notice' becomes 'see' (notice can mean to spot or see).
'pool' becomes 'pond' (synonyms).
'internally' is an insertion indicator.
'see' placed around 'pond' is 'SPONDEE'.
'is' acts as a link.
(Other definitions for spondee that I've seen before include "Metric foot of two long syllables" , "bit of verse" , "No speed required for poetic metrical foot" .)