Chicks raised wing as indicator of arrival (8)
I believe the answer is:
doorbell
'indicator of arrival' is the definition.
'chicks raised wing' is the wordplay.
'chicks' becomes 'brood' (number of young birds hatched at the same time).
'raised' is a reversal indicator.
'wing' becomes 'ell' (ell is a kind of wing).
'brood' back-to-front is 'doorb'.
'doorb'+'ell'='DOORBELL'
'as' acts as a link.
(Other definitions for doorbell that I've seen before include "which visitors use" , "It's rung by visitors" , "What one rings to be let in" , "Ring it for admittance" , "It announces a caller" .)