Heading for Dubrovnik and Split, having lots of energy (6)
I believe the answer is:
driven
'having lots of energy' is the definition.
'heading for dubrovnik and split' is the wordplay.
'heading for' says to take the initial letters.
'and' is a charade indicator (letters next to each other).
'split' becomes 'riven' (I've seen this before).
The first letter of 'dubrovnik' is 'd'.
'd'+'riven'='DRIVEN'
(Other definitions for driven that I've seen before include "Determined" , "(Psychologically) impelled" , "Urges or conveyed, perhaps in car" , "Propelled like a hard bargain" , "Strongly motivated to succeed" .)