Goodness, what a shame it would be to lose heart! (5)
I believe the answer is:
piety
'goodness what a shame it' is the definition.
I can't tell whether this defines the answer.
'would be to lose heart' is the wordplay.
'would' becomes 'pie' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'be' becomes 'tally' (tallying is a kind of being).
'to lose heart' says to hollow out the word (remove centre letters) (I've seen 'losing heart' mean this).
'tally' with its centre removed is 'ty'.
'pie'+'ty'='PIETY'
Can you help me to learn more?
(Other definitions for piety that I've seen before include "State of being devout in religion" , "Quality of being religious" , "Being faithful" , "Spirituality" , "Religious feeling" .)