Deception involving secret plan with fees (5,9)
I believe the answer is:
false pretences
'deception' is the definition.
(I've seen this before)
'involving secret plan with fees' is the wordplay.
'involving' is an anagram indicator.
'with' means one lot of letters go next to another.
'secret'+'plan'='secretplan'
'secretplan' put after 'fees' is 'feessecretplan'.
'feessecretplan' anagrammed gives 'FALSE PRETENCES'.
(Other definitions for false pretences that I've seen before include "deception" , "Behaviour intended to deceive" , "fraud" .)