Crossword Genius

Expression of annoyance when finding son's fake dog-rose, possibly (3,8,4)

Ross

I believe the answer is:

for goodness sake

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'expression of annoyance when' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.

'son's fake dog-rose possibly' is the wordplay.
'possibly' indicates an anagram.
'sons'+'fake'+'dog'+'rose'='sonsfakedogrose'
'sonsfakedogrose' with letters rearranged gives 'FOR GOODNESS SAKE'.

'finding' acts as a link.

Can you help me to learn more?

(Other definitions for for goodness sake that I've seen before include "Words of exasperation" , "please!" , "Really!" .)

I've seen this clue in The Daily Express.
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