Tokyo gangsters showing physical and mental discipline (4)
I believe the answer is:
yoga
'mental discipline' is the definition.
(I've seen this in another clue)
'tokyo gangsters showing' is the wordplay.
'showing' indicates the answer is hidden within the clue (the answer is shown in the clue).
'YOGA' is hidden in the letters of 'tokyo gangsters'.
'physical and' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for yoga that I've seen before include "Posturing" , "Type of exercise" , "Relaxing Hindu spiritual discipline" , "Healthy exercises" , "Hindu course of exercises and postures" .)