Steel structure in creepy London (5)
I believe the answer is:
pylon
'steel structure' is the definition.
(I've seen this before)
'in creepy london' is the wordplay.
'in' says the answer is hidden in the clue.
'PYLON' is hidden in the letters of 'creepy london'.
(Other definitions for pylon that I've seen before include "Electricity grid construction" , "Power-cable support" , "Grid cable support" , "Electricity cable support" , "Tower supporting power lines" .)