Tie the top there carelessly (6)
I believe the answer is:
tether
'tie' is the definition.
(I've seen this in another clue)
'the top there carelessly' is the wordplay.
'top' indicates taking the first letters.
'carelessly' indicates anagramming the letters.
The initial letter of 'the' is 't'.
'there' is an anagram of 'ether'.
't'+'ether'='TETHER'
(Other definitions for tether that I've seen before include "Restraining rope for animals" , "Hold by a rope" , "Rope to hobble a horse" , "restrain boxers, say" , "Rope; the exasperated at the end of it" .)