Extensioncord

4 clues
Power aid
A fan might need one
Electrical lengthener
It's often attached to Christmas lights
Similar answers:
Anextensionofmy
Coextensiveness
Extensible
Extension
Extensionaccord
Extensioncord
Extensioncored
Extensioncourse
Extensionheadache
Extensionladder
Extensionladders
Extensionrecord
Extensions
Extensive
Extensivedamage
Extensor
Extensors
Fileanextension
Fileextension
Hairextensions