Howl worried upper-class Liberal repeatedly at first (7)
I believe the answer is:
ululate
'howl' is the definition.
(synonyms)
'worried upper-class liberal repeatedly at first' is the wordplay.
'worried' becomes 'ate' (something worrying may eat someone up).
'upper-class' becomes 'u' (similar in meaning).
'liberal' becomes 'l' (abbreviation).
'repeatedly' indicates the doubling of some letters.
'at first' says to put letters next to each other.
'u'+'l'='ul'
'ul' duplicated is 'ulul'.
'ate' put after 'ulul' is 'ULULATE'.
(Other definitions for ululate that I've seen before include "Give a hoot" , "Wail or lament loudly" , "Emit long loud cries" , "Howl with grief" , "Express grief" .)