Directions help with plate that is repaired very quickly, some say (5,4)
I believe the answer is:
least said
'that is repaired very quickly some say' is the definition.
(as in the phrase 'least said, soonest mended')
'directions help with plate' is the wordplay.
'directions' becomes 'easts' (east is a kind of direction).
'help' becomes 'aid' (synonyms).
'with' means one lot of letters go next to another.
'plate' becomes 'l' (from the L-plate that Learner drivers use).
'easts'+'aid'='eastsaid'
'eastsaid' put after 'l' is 'LEAST SAID'.
(Another definition for least said that I've seen is " ` `..... ...., soonest mended' '".)