Free of gridlock (3)
I believe the answer is:
rid
'free' is the definition.
(to be free of something is to be rid of it)
'of gridlock' is the wordplay.
'of' indicates a hidden word.
'RID' can be found hidden inside 'gridlock'.
(Other definitions for rid that I've seen before include "Free (someone of something unwanted)" , "Free from something unpleasant" , "Free (person of affliction)" , "Free, relieve" , "Clear, remove" .)