Without a second thought, had fun too excitedly (3,2,4)
I believe the answer is:
out of hand
'without a second thought' is the definition.
'had fun too excitedly' is the wordplay.
'excitedly' is an anagram indicator.
'had'+'fun'+'too'='hadfuntoo'
'hadfuntoo' anagrammed gives 'OUT-OF-HAND'.
(Other definitions for out of hand that I've seen before include "So get pet bird fed" , "How one might feed dog" , "Beyond control" , "Banana so" , "lacking in control" .)