Go very quietly around Mile End! (3)
I believe the answer is:
pep
'go' is the definition.
(both can mean energy or vitality)
'quietly around mile end' is the wordplay.
'quietly' becomes 'pp' (musical abbreviation for pianissimo).
'around' indicates putting letters inside.
'end' indicates one should take the final letters.
The last letter of 'mile' is 'e'.
'pp' enclosing 'e' is 'PEP'.
'very' is the link.
(Other definitions for pep that I've seen before include "Palindrome for vigour" , "Palindromic vim and vigour" , "Energy or enthusiasm" , "Ginger; tax-free investment" , "Get-up-and-go" .)