Rider favouring face guard almost to the end (7)
I believe the answer is:
proviso
'rider' is the definition.
(I've seen this before)
'favouring face guard almost to the end' is the wordplay.
'favouring' becomes 'pro' (being in favour of something).
'face' says to put letters next to each other.
'guard' becomes 'visor' (a visor is a guard for one's eyes).
'almost to the end' means to remove the last letter (most but not all of the word).
'visor' with its last letter taken away is 'viso'.
'pro'+'viso'='PROVISO'
(Other definitions for proviso that I've seen before include "Stipulation (in contract)" , "Condition attached to an agreement" , "Condition of stipulation of an agreement" , "Stipulated condition" , "Clause in contract" .)