Get on strike with upright character — rich sort? (3,2,3)
I believe the answer is:
hit it off
'get on' is the definition.
(I've seen this before)
'strike with upright character rich sort?' is the wordplay.
'strike' becomes 'hit' (synonyms).
'with' is a charade indicator (letters next to each other).
'upright character' becomes 'I' (vertical letter of the alphabet).
'rich sort?' becomes 'toff' (I can't explain this - if you can you should believe this answer much more).
'hit'+'i'+'toff'='HIT IT OFF'
Can you help me to learn more?
(Other definitions for hit it off that I've seen before include "Develop a good friendly relationship" , "Click with someone" , "Get on well with - or knock from position?" , "Become compatible and friendly" , "Become immediate friends" .)