Look fearful when they immerse them in boiling water (6)
I believe the answer is:
blanch
'boiling water' is the definition.
The answer and definition can be both related to bodily activities as well as being verbs in their base form.
Maybe there's a link between them I don't understand?
'look fearful when they immerse them' is the wordplay.
I cannot quite understand how this works, but
'look' could be 'la' (I've seen this in other clues) and 'la' is found within the answer.
This explanation may well be incorrect...
'in' acts as a link.
Can you help me to learn more?
(Other definitions for blanch that I've seen before include "Make or become pale" , "(Of vegetables) cook briefly in boiling water" , "Scald briefly, then drain" , "Remove the colour, turn white" , "Go white as with fear" .)