Aim at regular leach in soil (6)
I believe the answer is:
direct
'aim at' is the definition.
(synonyms)
'regular leach in soil' is the wordplay.
'regular' indicates alternate letters.
'in' is an insertion indicator.
'soil' becomes 'dirt' (synonyms).
The alternate letters of 'leach' are 'ec'.
'ec' going within 'dirt' is 'DIRECT'.
(Other definitions for direct that I've seen before include "Command to be straight" , "Immediate; organise (e.g. play)" , "'Straight, without deviation (6)'" , "Frank; unambiguous" , "Guide the actors in plays and films" .)