The number of oaks in Kent (5)
I believe the answer is:
seven
'the number' is the definition.
(seven is a kind of number)
'oaks in kent' is the wordplay.
I cannot really see how this works, but
'kent' could be 'se' (Kent is part of the South East of England) and 'se' is located in the answer.
The remaining letters 'ven' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'of' is the link.
Can you help me to learn more?
(Other definitions for seven that I've seen before include "Little friends of ..." , "VII" , "number of swans aswimming" , "Figure of dwarfs?" , "Prime number" .)