Happy Londoners have powerful support (5)

I believe the answer is:

pylon

I'm a little stuck... Click here to teach me more about this clue!

'powerful support' is the definition.
'pylon' can be an answer for 'support'. I'm unsure of the 'powerful' bit.

'happy londoners have' is the wordplay.
'have' indicates the answer is hidden within the clue.
'PYLON' is hidden within 'happy londoners'.

Can you help me to learn more?

(Other definitions for pylon that I've seen before include "Elec. cable tower" , "Power cable support" , "Steel structure carrying cables" , "Electricity cable support" , "Power cables supporter" .)

I've seen this clue in The Mirror.

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