Five observed all round as a somewhat larger number (5)
I believe the answer is:
seven
'a somewhat larger number' is the definition.
'seven' can be an answer for 'number' (seven is a kind of whole number). I'm not certain of the 'a somewhat larger' bit.
'five observed all round' is the wordplay.
'five' becomes 'V' (Roman numeral).
'observed' becomes 'seen' (synonyms).
'all round' is an insertion indicator.
'v' inserted within 'seen' is 'SEVEN'.
'as' is the link.
Can you help me to learn more?
(Other definitions for seven that I've seen before include "Wonders of the World - Deadly Sins" , "equivalent of uproar [7D]" , "Film" , "Theme of exotic dance" , "Cube root of 343" .)