Head of state has more than enough to try (6)
I believe the answer is:
sample
'try' is the definition.
('sample' can be a synonym of 'try')
'head of state has more than enough' is the wordplay.
'head of' indicates taking the first letters.
'has' says to put letters next to each other.
'more than enough' becomes 'ample' (I've seen this before).
The initial letter of 'state' is 's'.
's'+'ample'='SAMPLE'
'to' acts as a link.
(Other definitions for sample that I've seen before include "Model" , "Taste; specimen" , "Small part representing the whole" , "Small part representative of the whole" , "Representative portion" .)