Ineffectual type sees king in depression (4)
I believe the answer is:
drip
'ineffectual type' is the definition.
(I've seen this before)
'king in depression' is the wordplay.
'king' becomes 'r' (r is abbreviation for rex).
'in' means one lot of letters goes inside another.
'depression' becomes 'dip' (dip is a kind of depression).
'r' inserted within 'dip' is 'DRIP'.
'sees' is the link.
(Other definitions for drip that I've seen before include "Weed - seep" , "Leak slowly" , "Liquid falling in small golbules, or a dull person" , "Insubstantial person - trickle" , "wet blanket" .)