Single maiden beginning to step into lake for dip (7)
I believe the answer is:
immerse
'dip' is the definition.
(I've seen this in another clue)
'single maiden beginning to step into lake' is the wordplay.
'single' becomes 'i' (one).
'maiden' becomes 'm' (cricket abbreviation).
'beginning to' indicates taking the first letters.
'into' means one lot of letters goes inside another.
'lake' becomes 'mere' (mere is a kind of lake).
The initial letter of 'step' is 's'.
's' going into 'mere' is 'merse'.
'i'+'m'+'merse'='IMMERSE'
'for' is the link.
(Other definitions for immerse that I've seen before include "Engross" , "Dip totally into liquid" , "Engage deeply" , "Dunk" , "Steep - plunge" .)