Changing name to Mark, a friend abroad shows taste (5)
I believe the answer is:
umami
'taste' is the definition.
(I've seen this before)
'changing name to mark a friend abroad' is the wordplay.
'changing name' becomes 'u' (I can't explain this - if you can you should give a lot more credence to this answer).
'to mark' becomes 'm'.
'a friend abroad' becomes 'ami' (I've seen this in another clue).
'u'+'m'+'ami'='UMAMI'
'shows' is the link.
Can you help me to learn more?
(Other definitions for umami that I've seen before include "acquired taste perhaps" , "Savoury flavour" , "Fifth flavour" , "meaty taste" , "Savoury taste sensation produced by glutamates - I, a mum (anag)" .)