Sex is good: climax with that woman, husband's away (6)
I believe the answer is:
'sex' is the definition.
'good climax with that woman husband's away' is the wordplay.
I cannot quite understand how this works, but
'good' could be 'g' (abbreviation) and 'g' is found within the answer.
'climax' could be 'end' (climax can mean the end of something) and 'end' is located in the answer.
The remaining letters 'er' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
'is' is the link.
Can you help me to learn more?
(Other definitions for gender that I've seen before include "Sex category" , "Class such as female or male" , "Eg, male" , "Man or woman" , "What divides males and females" .)