Reach via a rickety gate that's about finished (3,2)
I believe the answer is:
get at
'reach' is the definition.
(I know that get at is a more specific form of the action reach)
'a rickety gate that's about finished' is the wordplay.
'a rickety' indicates an anagram.
'that's about finished' becomes 't' (I am not sure about this - if you are sure you should believe this answer much more).
'gate' with letters rearranged gives 'geta'.
'geta'+'t'='GET AT'
'via' is the link.
Can you help me to learn more?
(Other definitions for get at that I've seen before include "Pick on - gain access to" , "Reach - mean - attack verbally" , "Nobble; gain access to" , "Criticise (someone)" , "Unfairly influence" .)