Handy fencing manual occasionally gives a pre-set option (7)
I believe the answer is:
default
'a pre-set option' is the definition.
(as in a default setting)
'handy fencing manual occasionally' is the wordplay.
'handy' becomes 'deft' (I've seen this in another clue).
'fencing' means one lot of letters goes inside another (to fence can mean to contain or put a limit round).
'occasionally' means one should take alternating letters (letters taken at regular intervals or occasions).
The alternate letters of 'manual' are 'aul'.
'deft' enclosing 'aul' is 'DEFAULT'.
'gives' is the link.
(Other definitions for default that I've seen before include "Failure to fulfil an obligation" , "basic computer programming" , "Failure to pay" , "Not paying" , "Fail to make due payments" .)