County nicknamed the Garden of England (4)
I believe the answer is:
kent
'garden of england' is the definition.
(I've seen this before)
'county nicknamed the' is the wordplay.
I cannot quite see how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is present in the answer.
The remaining letters 'ken' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for kent that I've seen before include "Part of 1 25 [KING LEAR]" , "South-eastern county" , "Southern English county" , "English architect and landscape gardener" , "Knew (Scottish)" .)