Tower over toilet man (4)
I believe the answer is:
loom
'tower over' is the definition.
(I've seen this in another clue)
'toilet man' is the wordplay.
'toilet' becomes 'loo' (loo can informally mean a toilet).
'man' becomes 'm' (M is an abbreviation for male or masculine).
'loo'+'m'='LOOM'
(Other definitions for loom that I've seen before include "Of future event, seem ominously close" , "Appear indistinctly, in threatening form" , "Rise up threateningly ahead" , "Appear large and indistinct, to weave?" , "Weaving frame - seem ominously close" .)