Return to office as long as railway guards supply power (9)
I believe the answer is:
electrify
'power' is the definition.
Although both the answer and definition are verbs in their base form, I cannot see how they can define each other.
'return to office as long as railway guards' is the wordplay.
I cannot really see how this works, but
'return' could be 'elect' (I've seen this before) and 'elect' is located in the answer.
'railway' could be 'r' (eg in Great Western Railway) and 'r' is present in the answer.
This may be the basis of clue (or it may be nonsense).
'supply' acts as a link.
Can you help me to learn more?
(Other definitions for electrify that I've seen before include "Cause thrilling excitement in (someone)" , "Charge with power" , "Supply power to; shock, thrill" , "Fire" , "Galvanise - animate" .)