Up-to-date tent, with electric current, mostly cool (7)
I believe the answer is:
topical
'up-to-date' is the definition.
(thesaurus)
'tent with electric current mostly cool' is the wordplay.
'tent' becomes 'top' (top is a kind of tent).
'with' is a charade indicator (letters next to each other).
'electric current' becomes 'I' (physics symbol).
'mostly cool' becomes 'cal' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'top'+'i'+'cal'='TOPICAL'
Can you help me to learn more?
(Other definitions for topical that I've seen before include "About current events in Capitol" , "Relating to current affairs" , "Of interest at the present time" , "Dealing with current affairs" , "currently newsworthy" .)