Alert Charlie taking the lead in sale (7)
I believe the answer is:
caution
'alert' is the definition.
(thesaurus)
'charlie taking the lead in sale' is the wordplay.
I cannot quite see how this works, but
'charlie' could be 'c' (phonetic alphabet: alpha, bravo, charlie etc.) and 'c' is found within the answer.
'taking' could be 'on' (eg one taking drugs is 'on' drugs) and 'on' is present in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for caution that I've seen before include "Give a warning to" , "Warning - prudence" , "Circumspection" , "Care taken to avoid danger" , "Legal warning" .)